Tissue motion is usually measured by use of a method known as Tissue Doppler Imaging consisting in recording the successive responses of a medium to ultrasonic excitations generated at a given repetition rate, the phase shift between two successive response signals being directly related to the motion vector component along the excitation beam axis. However, this method only enables the measurement of the motion vector component along this axis.
On the other hand, a classic 3D echography method is not likely to provide a satisfactory solution, because it is not practically possible to record simultaneously several orientations which could allow the reconstruction of the overall motion vector due to the required complexity and high cost it involves and/or accessibility constraints.